fix class name of x2paddle_code.py

[bigbosskai]

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If this PR add new model support, please update model_zoo.md and add model to out test model zoos(@wjj19950828)

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[wjj19950828]

@bigbosskai hi，感谢贡献～

可以在conversation里描述一下具体解决了什么问题，做出了哪些贡献